Chloroform–Methanol Extraction of Chlorophyll a

1985 ◽  
Vol 42 (1) ◽  
pp. 38-43 ◽  
Author(s):  
Lindsay W. Wood
Keyword(s):  
Hydrogen Sulfide ◽  
Chlorophyll A ◽  
Room Temperature ◽  
Ph Control ◽  
Absolute Methanol ◽  
Separatory Funnel ◽  
Chloroform Layer ◽  
Extraction Mixture ◽  
Chloroform Methanol ◽  
Algal Cultures

Chloroform–methanol (2:1, v/v) extracts significantly more (P < 0.001) chlorophyll a from algal cultures and from freshwater and seawater microcosms than does dimethyl sulfoxide, methanol, absolute methanol with hydrogen sulfide, or 90% acetone. For chlorophyte cultures it yields 97% or more of the chlorophyll a within a 4-h steeping period without grinding. It can be used with both calibrated spectrophotometry and fluorometric instrumentation. Sample filtration onto MgCO3-coated filters is recommended to ensure buffering of the extraction mixture. Holding the filters in chloroform–methanol at 4 °C or room temperature in the dark prevents loss of chlorophyll a for at least 10 d. More refined analyses of phaeophytin and other chlorophylls require the use of chloroform–methanol–water (2:2:1.8, by volume) and placement in a separatory funnel. After 24 h the lower (chloroform) layer contains all of the chlorophyll. Strict pH control is required for pheophytin determinations.

PITTING MECHANISM OF MILD STEEL IN MARGINALLY SOUR ENVIRONMENTS: PIT PROPAGATION BASED ON ACIDIFICATION BY CATALYTIC OXIDATION OF DISSOLVED HYDROGEN SULFIDE

CORROSION ◽  
10.5006/3858 ◽  
2021 ◽  
Author(s):  
Wei Zhang ◽  
Bruce Brown ◽  
David Young ◽  
Stephen Smith ◽  
Sytze Huizinga ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Mild Steel ◽  
Experimental Measurement ◽  
Thermodynamic Calculation ◽  
Room Temperature ◽  
Steel Surface ◽  
Saturation Degree ◽  
Transitional Metal ◽  
Dissolved Hydrogen ◽  
Dissolved O2

The present work studies pit propagation in marginally sour environments and proposes a credible mechanism. Both thermodynamic calculation and experimental measurement confirmed that H2S can be oxidized by traces of dissolved O2 into SO42- and H+ in the aqueous solutions near room temperature with the transitional metal ions serving as a catalyst. This acidification phenomenon would be more effective near the steel surface, especially inside a pit, where Fe2+ ions are most abundant. Therefore, the saturation degree of mackinawite would be lower inside the pit, which would prohibit the pitting from annihilation.

Preparation of Sorbent Loaded with Nano-CuO for Room Temperature to Remove of Hydrogen Sulfide

2013 ◽  
Vol 475-476 ◽  
pp. 1329-1333 ◽  
Author(s):  
Fen Li ◽  
Jin Wei ◽  
Ying Yang ◽  
Guang Hui Yang ◽  
Tao Lei
Keyword(s):  
Grain Size ◽  
Hydrogen Sulfide ◽  
Metal Oxide ◽  
Copper Oxide ◽  
Calcination Temperature ◽  
Room Temperature ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Coconut Shell ◽  
Load Rate

In this paper, an efficient metal oxide sorbents for the deep removal of H2S were synthesized using equal volume impregnation (EVIM) method. Modified coconut shell charcoal was selected as support to deposite the particles of copper oxide onto the surface. And copper nitrate were selected as the active component precursors in the preparation process of sorbents. Sorption experiments were carried out at room temperature in fixed-bed reactor. The grain size and crystal form of loading metals were characterized by X-ray diffraction (XRD). We investigated the effects of modifier onto coconut shell charcoal, load rate of metal oxide and calcination temperature on the desulfurization activity of the sorbent. Results show that the best modifier for coconut shell charcoal is KOH, which is significantly better than the other modifiers. And the optimum load rate is 20%(wt), the optimum calcination temperature is 300°C. Copper oxide onto the surface of modified coconut shell charcoal proved to be monoclinic nanoparticles with grain size of 18.7nm. Sulfidation test was carried out on the condition of i) the concentration of hydrogen sulfide gas (mixed with nitrogen ) is 1024.2ppm and ii) gas velocity is 20ml/min, iii) 0.1g sample in the middle of the fixed-bed reactor (length: 450 mm, interior diameter: 5 mm) to test. The sample show excellent sulfur removal efficiency and its breakthrough time is up to 287 min on this condition.

A PROCEDURE FOR RAPID RECOVERY OF AFLATOXINS FROM CHEESE AND OTHER FOODS1

1971 ◽  
Vol 34 (3) ◽  
pp. 119-123 ◽  
Author(s):  
C. N. Shih ◽  
E. H. Marth
Keyword(s):  
Liquid Culture ◽  
Culture Medium ◽  
Peanut Butter ◽  
Corn Meal ◽  
Water Fraction ◽  
Food Residue ◽  
Liquid Culture Medium ◽  
Chloroform Layer ◽  
Sequential Addition ◽  
Chloroform Methanol

A rapid and efficient method has been developed to recover aflatoxin from cheese and other foods. The procedure involves: (a) blending the sample with a mixture of chloroform, methanol, and water (solvents are used in such proportions that a miscible (monophasic) system is formed, (b) adding more chloroform and water so the mixture becomes biphasic, (c) filtering to remove the food residue, (d) separating the lower chloroform layer which contains virtually all of the aflatoxin, and (e) purification, if necessary, of the material in step (d) after it has been concentrated. Purification is achieved by sequential addition of methanol, water, and hexane; recovery of tho methanol-water fraction; and extraction of aflatoxins from it with chloroform. Purification can be eliminated if the substrate contains little or no lipid or pigment which, if present, interfere with thin-layer chromaographic analysis. Extraction can be done in approximately 35 min and purification in approximately 20 min. When aflatoxins were added to various substrates, the method recovered 92–98% B1 and 96–100% G1 from rice; 95–96% B1 and 90–95% G1 from peanut butter; 93–94% B1 and 92–98% G1 from Cheddar cheese; 100% B1 and G1 from corn meal; 91–100% B1, 91–100% B2, 90–96% G1, and 92–100% G2 from brick cheese; and 97–100% B1, 95–100% B2, 92–100% G1, and 98–100% G2 from a liquid culture medium.

scholarly journals Approaches towards the synthesis of a 2,9,16,23-tetrasubstituted phthalocyanine as a pure isomer

1988 ◽  
Vol 66 (5) ◽  
pp. 1059-1064 ◽  
Author(s):  
Shafrira Greenberg ◽  
A. B. P. Lever ◽  
Clifford C. Leznoff
Keyword(s):  
Hydrogen Sulfide ◽  
Low Temperature ◽  
Zinc Acetate ◽  
Room Temperature ◽  
Pure Isomer

Treatment of 4-neopentoxyphthalonitrile with hydrogen sulfide gas yielded 1-imino-6-neopentoxy-3-thioisoindoline and 1-imino-5-neopentoxy-3-thioisoindoline, which on alkylation with iodomethane gave 1-imino-3-methylthio-6-neopentoxyiso-indolenine and 1-imino-3-methylthio-5-neopentoxyisoindolenine. The methylthioisoindolenines readily condensed at room temperature to a mixture of tetrasubstituted phthalocyanines and a series of linear open-chained purple compounds characteristic of isoindigos, while condensation at −20 °C in the presence of zinc acetate gave, in at least one experiment, 2,9,16,23-tetraneo-pentoxyphthalocyanine as a pure isomer. The low temperature formation of phthalocyanines is remarkable and the syntheses described herein provide guidelines for the synthesis of pure isomers of 2,9,16,23-tetrasubstituted phthalocyanines. The purple and red compounds are shown to have isoindigo structures rather than a ring-opened phthalocyanine structure as previously reported.

The Electrochemical Reduction of Hydrogen Sulfide on Platinum in Several Room Temperature Ionic Liquids

2008 ◽  
Vol 112 (20) ◽  
pp. 7725-7730 ◽  
Author(s):  
Aoife M. O’Mahony ◽  
Debbie S. Silvester ◽  
Leigh Aldous ◽  
Christopher Hardacre ◽  
Richard G. Compton
Keyword(s):  
Ionic Liquids ◽  
Hydrogen Sulfide ◽  
Electrochemical Reduction ◽  
Room Temperature ◽  
Room Temperature Ionic Liquids

Comparison of Hydrogen Sulfide Sensing Properties between Multiple-Walled Carbon Nanotubes (MWNTs) and MWNTs-HAuCl4 Materials

2014 ◽  
Vol 936 ◽  
pp. 310-314
Author(s):  
Si Xuan He ◽  
Guang Zhong Xie ◽  
Ya Dong Jiang ◽  
Guang Di Zhang ◽  
Yong Zhou
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Scanning Electron Microscopy ◽  
Hydrogen Sulfide ◽  
Response Time ◽  
Room Temperature ◽  
The Other ◽  
High Toxicity ◽  
Walled Carbon Nanotubes ◽  
Scanning Electron

The rapid and precise detection of hydrogen sulfide (H2S) has great significance due to its high toxicity. In this work, the response properties of multiple-walled carbon nanotubes (MWNTs) and MWNTs-HAuCl4 to H2S at room temperature were compared. Scanning electron microscopy (SEM) technique was used to characterize MWNTs and MWNTs-HAuCl4 films. It was found that sensors with MWNTs-HAuCl4 exhibited much higher response value. On the other hand, sensors with MWNTs were observed to have faster response time and better recovery properties.

scholarly journals Structure of the Red Fluorescence Band in Chloroplasts

1966 ◽  
Vol 49 (4) ◽  
pp. 763-780 ◽  
Author(s):  
Govindjee ◽  
Louisa Yang
Keyword(s):  
Chlorophyll A ◽  
Room Temperature ◽  
Emission Spectra ◽  
Matrix Analysis ◽  
Spinach Chloroplast ◽  
Excitation Spectra ◽  
Temperature Changes ◽  
Pigment System ◽  
Fluorescence Efficiency ◽  
Chlorophyll A And B

Using Weber's method of "matrix analysis" for the estimation of the number of fluorescent species contributing to the emission of a sample, it is shown that the fluorescence1 band in spinach chloroplast fragments at room temperature originates in two species of chlorophyll a. Emission spectra obtained upon excitation with different wavelengths of light (preferentially absorbed in chlorophyll a or b) are presented. Upon cooling to - 196°C, the fluorescence efficiency increases about twentyfold. Two additional bands, that now appear at 696 and 735 mµ, suggest the participation of four molecular species. Emission spectra observed at different concentrations of chloroplast fragments with excitation in chlorophyll a and b and excitation spectra for different concentrations of chloroplast fragments and measurements at 685 and 760 mµ are presented. Two of the four emission bands may belong to pigment system I and two to system II. The 685, 696, and 738 mµ bands respond differently to temperature changes. In the -196°C to -150°C range, the intensity of the 685 mµ band remains constant, and that of the 696 mµ band decreases twice as fast as that of the 738 mµ band.

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